#include <iostream>
#include <cstring>

using namespace std;

char s[512];

int main()
{   
    int n;
    int len = 0;

    cin >> n;
    for(int i = 1; i <= n; i++) {
        strcat(s+len+1, s);
        s[len] = 'A' + i - 1;
        len = strlen(s);
    }
    cout << s << endl;


    return 0;
}

